Optical flame detectors are designed to distinguish optical energy emitted by flames from those emitted by other sources. The optical energy may be in ultraviolet through infrared wavelengths depending on the flame detector type. Verifying the ability of flame detectors to detect optical radiation is necessary, in order to establish and verify the response of the safety system to radiation in the same wavelengths and modulation frequencies as those produced by real flames. Conducting such verification in an industrial setting can be challenging due to the likely disruption of safety functions and consequent operational cost. Therefore, it is often desired in field installations that a remote optical test source be auto-detected and able to test the flame detection system without the need to bypass alarms. The need for such remote testing methods is well established, especially as flame detectors are often mounted in areas of restricted access and elevation pointing down, and auto-detection must occur over distances of tens of meters. Such proof testing is a requirement of safety instrumented systems to demonstrate that everything is working and performing as expected.